1. Technical Field
The present invention relates to a sensor device.
2. Related Art
There are known sensor devices which, for example, measure the state of corrosion of a reinforcing bar in concrete (e.g., see Japanese Laid-Open Patent Application Publication No. H06-222033).
Typically, the concrete in a concrete structure immediately after construction exhibits a strong alkalinity. For this reason, the reinforcing bars in a concrete structure immediately after construction have a passivation film formed on the surface thereof and are therefore stable. However, in a concrete structure that is affected after construction by acid rain, exhaust gas, and the like, the concrete will be gradually acidified (neutralization), and the reinforcing bars will therefore corrode. With concrete structures, the reinforcing bars also corrode due to chloride ions that infiltrate the concrete.
For example, in the device recited in the above mentioned publication, a probe provided with a reference electrode and a counter electrode is embedded in concrete and measures the polarization resistance and changes in electric potential caused by the corrosion of the reinforcing bars, whereby the corrosion of the reinforcing bars is predicted.
However, with this device, it is not possible to identify whether the cause of the corrosion of the reinforcing bars is due to chloride ions that infiltrate the concrete or due to neutralization of the concrete, and as a result, there is the problem that it is not possible to perform suitable preservation of the concrete structure.